Dental grinding tool



Feb 21, 1956 v. H. CARPENTER DENTAL GRINDING TOOL Filed Feb. 3, 1955 United States Patent O M DENTAL GRINDING TOOL Victor H. Carpenter, Boston, Mass.

Application February 3, 1953, Serial No. 334,849

3 Claims. (Cl. 32-59) This invention relates to a special dental grinding tool for grinding away a portion of the enamel of a tooth which is to be capped with a jacket crown having an exterior contour closely approximating that of the original tooth and extending preferably to the gum line. The jacket crown is cemented on the stump of the tooth to take the place of the portions of the tooth which have been broken or ground olf. In order to provide a positive seat for the rim edges of the crown, the enamel of the tooth is ground off in such a way as to provide a shoulder of predetermined width extending around the periphery of the tooth, preferably at or near the gum line, so as to take a considerable portion of the thrust of biting pressure on the crown and to reduce the liability of the crown to rock on its base and thus to become loose.

In grinding off the enamel of a tooth difliculty has been experienced in operating accurately on the inner and outer faces of the tooth with the tools heretofore available. It is an object of the present invention to provide a grinding tool specially constructed for grinding off these faces, preferably after the side faces of the tooth which face the adjacent teeth have already been ground with the formation of segments of the peripheral shoulder.

For a more complete understanding of the invention reference may be had to the following description thereof and to the drawings of which- Figure 1 is a perspective view of a set of teeth, one incisor being broken, and a grinding tool in position to start grinding a side face of the broken incisor;

Figure 2 is a fragmentary elevational view, on a larger scale, of the incisor shown in Figure l, the adjacent teeth on either side and a grinding tool operating on the incisor;

Figure 3 is a section on the line 3 3 of Figure 2;

Figure 4 is a perspective view of the incisor after its side faces have been ground;

Figure 5 is an elevational view on a smaller scale of a tool embodying the invention;

Figure 6 is a fragmentary perspective view, on a larger scale, of the tool shown in Figure 5;

Figure 7 is an elevational view of a tooth showing the operation thereon of the tool shown in Figures 5 and 6; i

Figure 8 is a perspective view of the tooth which is ready for a jacket crown;

Figure 9 is a fragmentary plan View on a larger scale of a jaw with teeth thereon, indicating the movements of the grinding tool on the inner and outer faces of one of the teeth;

Figure 10 is a fragmentary elevation of a tooth stump and a sectional view of a crown to be mounted thereon; and

Figure 1l is a sectional view of the tooth stump shown in Figure 10 having the crown mounted thereon.

Figure 1 shows a jaw 10 having a set of teeth, an incisor 12 being indicated as broken. The method of capping broken or otherwise defective teeth to which the 2,735,181 Patented Feb. 2l, 1956 tool embodying the invention applies includes grinding ol the remaining enamel of the tooth, preferably down to the gum line, the enamel being ground away in such a manner as to leave a well defined shoulder extending around the periphery of the tooth as a base on which edge or rim a jacket crown can positively engage. In grinding olf the enamel surface, the side faces of the tooth are preferably ground by a tool such as is shown in Figure 1, this tool consisting of a stem 14 on which is a thin disk 16 having an abrasive surface of diamond dust, diamond chips, carborundum dust or other ei'licient abrasive material. This disk is employed to grind off the enamel on the side faces of the tooth, that is, the faces which are opposite to the adjacent teeth 18 and 20. The tool is provided with a thin ilange element 22, preferably of metal, which acts as a guide member to prevent the disk from cutting into the tooth further than the thickness of the abrasive disk 16. Thus the shoulders 24 which are formed by the grinding action of the disk at the sides of the tooth 12 are substantially equal to the thickness of the disk 16 as indicated in Figure 2.

Diculty has been heretofore experienced in the grinding of inner and outer faces of the tooth, that is, carrying on a grinding operation from the condition illustrated in Figure 4 which shows the stump of the tooth 12 after the side faces have been ground. For this purpose a special tool is provided, according to the present invention, as illustrated in Figures 5, 6 and 7. This tool comprises a stem 30, one end of which is adapted to be gripped in the customary chuck 32. On the other end portion of the stem is mounted the elongated abrasive element 34 which can be cylindrical in shape orcan taper in either direction. As shown, this element tapers slightly from the end 36. The end face at the end 36 is preferably slightly reentrant, forming a shallow conical recess. A relatively short guide pin 40 projects from the center of the end face 36 and is coaxial with the stem 30. The radial width of the end face 36 from any point of the circumference thereof to the pin 40 is equal to the width of the shoulder which is to be cut on the tooth, as is evident from Figure 7.

After the side faces of a tooth have been ground off by a suitable tool such as the disk 16 so as to form shoulders 24 as indicated in Figure 4, a tool like that shown in Figure 5, having the abrasive element 34, is applied to the inner and outer faces of the tooth stump as indicated in Figure 7 so as to grind oi'f these faces and to form shoulder segments which join with the segments 24 to form a shoulder 44 of uniform width extending around the entire periphery of the tooth as indicated in Figure 8. This shoulder preferably but not necessarily follows the gum line around the periphery of the tooth. The tooth stump is now ready to receive a jacket crown 50 which is preferably shaped so that it has an exterior contour closely resembling that of the original tooth. When the crown is ixed in place it will then resemble the origi nal perfect tooth. The rim 52 of the crown is shaped to t on the peripheral shoulder of the tooth stump so that it has a positive engagement therewith. A suitable cement 54 is employed to secure the crown in place on the stump.

I claim:

l. A dental grinding tool comprising a stem, an approximately cylindrical abrasive element on an end portion of said stem, said element having an end face in the form of a shallow conical concavity, and a guide pin coaxial with said stem projecting from said end of the abrasive element.

2. A dental grinding tool as set forth in claim 1, the diameter of said abrasive element tapering slightly from a maximum at said end face.

3. A dental tool for cutting away a surface layer from teeth, comprising, au elongated approximately cylindrical, material-removing member, a relatively short guide pin projecting coaxially from one end of said member, and va stem projecting coaxialy from the other end of said member, said member tapering slightly from a maximum diameter at the end from which the pinvprojects to the end from which the stem projects.

References Cited in the tile of this patent UNITED STATES PATENTS 2,453,696 Brooks Nov. 16, 1948 OTHER REFERENCES Dental Cosmos, 1914, page 822, Fig. 58. Div. 55.)

Swearingen July 31, 1951 (Copy in The Improved Carborundum Brand Dental Goods,

(Avail- 

